Calciborite

{{Short description|Inoborate mineral}}

{{Infobox mineral

| name = Calciborite

| category = Inoborates

| boxwidth =

| boxbgcolor =

| image = Calciborite.jpg

| imagesize =

| caption = White crystals of calciborite from the type locality in Russia (Novofrolovskoye Deposit)

| formula = CaB₂O₄

| IMAsymbol=Cbo{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}

| molweight = 125.70 g/mol

| strunz = 6.BC.10

| system = Orthorhombic

| class = Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)

| symmetry = Pccn

| unit cell = a = 8.38 Å, b = 13.82 Å,
c = 5.00 Å; Z = 8

| color = White

| habit = Prismatic crystals and radial clusters

| twinning =

| cleavage = None

| fracture = Conchoidal to uneven

| tenacity =

| mohs = 3.5

| luster = Vitreous

| polish =

| refractive = n_α = 1.595 n_β = 1.654 n_γ = 1.670

| opticalprop = Biaxial (-)

| birefringence = δ = 0.075

| 2V = Measured: 54°

| dispersion =

| pleochroism =

| fluorescence=

| absorption =

| streak = White

| gravity = 2.878

| density =

| melt =

| fusibility =

| diagnostic =

| solubility =

| diaphaneity = Translucent

| other =

| references = [https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Calciborite Mineralienatlas][http://www.webmineral.com/data/Calciborite.shtml Calciborite Mineral Data from Webmineral][http://www.mindat.org/min-854.html Calciborite: Calciborite mineral information] from Mindat.org[http://rruff.geo.arizona.edu/doclib/hom/calciborite.pdf Handbook of Mineralogy]

}}

Calciborite, CaB₂O₄, is a rare calcium borate mineral.

It was first described in 1955 in the Novofrolovskoye copper–boron deposit, near Krasnoturinsk, Turinsk district, Northern Ural Mountains, Russia. It occurs in a skarn deposit formed in limestone adjacent to a quartz diorite intrusive. It occurs associated with: sibirskite (another rare calcium borate mineral), calcite, dolomite, garnet, magnetite and pyroxene. It has also been reported from the Fuka mine of Okayama Prefecture, Japan.